16 "github.com/anacrolix/log"
17 "github.com/anacrolix/missinggo"
18 "github.com/anacrolix/missinggo/iter"
19 "github.com/anacrolix/missinggo/v2/bitmap"
20 "github.com/anacrolix/missinggo/v2/prioritybitmap"
21 "github.com/anacrolix/multiless"
22 "github.com/anacrolix/torrent/metainfo"
24 "github.com/anacrolix/torrent/bencode"
25 "github.com/anacrolix/torrent/mse"
26 pp "github.com/anacrolix/torrent/peer_protocol"
29 type PeerSource string
32 PeerSourceTracker = "Tr"
33 PeerSourceIncoming = "I"
34 PeerSourceDhtGetPeers = "Hg" // Peers we found by searching a DHT.
35 PeerSourceDhtAnnouncePeer = "Ha" // Peers that were announced to us by a DHT.
37 // The peer was given directly, such as through a magnet link.
38 PeerSourceDirect = "M"
41 type peerRequestState struct {
45 type PeerRemoteAddr interface {
50 // First to ensure 64-bit alignment for atomics. See #262.
60 RemoteAddr PeerRemoteAddr
61 // True if the connection is operating over MSE obfuscation.
63 cryptoMethod mse.CryptoMethod
66 closed missinggo.Event
67 // Set true after we've added our ConnStats generated during handshake to
68 // other ConnStat instances as determined when the *Torrent became known.
69 reconciledHandshakeStats bool
71 lastMessageReceived time.Time
72 completedHandshake time.Time
73 lastUsefulChunkReceived time.Time
74 lastChunkSent time.Time
76 // Stuff controlled by the local peer.
78 lastBecameInterested time.Time
79 priorInterest time.Duration
81 lastStartedExpectingToReceiveChunks time.Time
82 cumulativeExpectedToReceiveChunks time.Duration
83 _chunksReceivedWhileExpecting int64
86 requests map[Request]struct{}
88 // Chunks that we might reasonably expect to receive from the peer. Due to
89 // latency, buffering, and implementation differences, we may receive
90 // chunks that are no longer in the set of requests actually want.
91 validReceiveChunks map[Request]int
92 // Indexed by metadata piece, set to true if posted and pending a
94 metadataRequests []bool
95 sentHaves bitmap.Bitmap
97 // Stuff controlled by the remote peer.
100 peerRequests map[Request]*peerRequestState
101 PeerPrefersEncryption bool // as indicated by 'e' field in extension handshake
103 // The pieces the peer has claimed to have.
104 _peerPieces bitmap.Bitmap
105 // The peer has everything. This can occur due to a special message, when
106 // we may not even know the number of pieces in the torrent yet.
108 // The highest possible number of pieces the torrent could have based on
109 // communication with the peer. Generally only useful until we have the
111 peerMinPieces pieceIndex
112 // Pieces we've accepted chunks for from the peer.
113 peerTouchedPieces map[pieceIndex]struct{}
114 peerAllowedFast bitmap.Bitmap
116 PeerMaxRequests int // Maximum pending requests the peer allows.
117 PeerExtensionIDs map[pp.ExtensionName]pp.ExtensionNumber
118 PeerClientName string
120 pieceInclination []int
121 _pieceRequestOrder prioritybitmap.PriorityBitmap
126 // Maintains the state of a BitTorrent-protocol based connection with a peer.
127 type PeerConn struct {
130 // A string that should identify the PeerConn's net.Conn endpoints. The net.Conn could
131 // be wrapping WebRTC, uTP, or TCP etc. Used in writing the conn status for peers.
136 PeerExtensionBytes pp.PeerExtensionBits
138 // The actual Conn, used for closing, and setting socket options.
140 // The Reader and Writer for this Conn, with hooks installed for stats,
141 // limiting, deadlines etc.
145 writeBuffer *bytes.Buffer
146 uploadTimer *time.Timer
152 func (cn *PeerConn) connStatusString() string {
153 return fmt.Sprintf("%+-55q %s %s", cn.PeerID, cn.PeerExtensionBytes, cn.connString)
156 func (cn *Peer) updateExpectingChunks() {
157 if cn.expectingChunks() {
158 if cn.lastStartedExpectingToReceiveChunks.IsZero() {
159 cn.lastStartedExpectingToReceiveChunks = time.Now()
162 if !cn.lastStartedExpectingToReceiveChunks.IsZero() {
163 cn.cumulativeExpectedToReceiveChunks += time.Since(cn.lastStartedExpectingToReceiveChunks)
164 cn.lastStartedExpectingToReceiveChunks = time.Time{}
169 func (cn *Peer) expectingChunks() bool {
170 if len(cn.requests) == 0 {
179 for r := range cn.requests {
180 if cn.peerAllowedFast.Contains(bitmap.BitIndex(r.Index)) {
187 // Returns true if the connection is over IPv6.
188 func (cn *PeerConn) ipv6() bool {
193 return len(ip) == net.IPv6len
196 // Returns true the if the dialer/initiator has the lower client peer ID. TODO: Find the
197 // specification for this.
198 func (cn *PeerConn) isPreferredDirection() bool {
199 return bytes.Compare(cn.t.cl.peerID[:], cn.PeerID[:]) < 0 == cn.outgoing
202 // Returns whether the left connection should be preferred over the right one,
203 // considering only their networking properties. If ok is false, we can't
205 func (l *PeerConn) hasPreferredNetworkOver(r *PeerConn) (left, ok bool) {
207 ml.NextBool(l.isPreferredDirection(), r.isPreferredDirection())
208 ml.NextBool(!l.utp(), !r.utp())
209 ml.NextBool(l.ipv6(), r.ipv6())
213 func (cn *Peer) cumInterest() time.Duration {
214 ret := cn.priorInterest
216 ret += time.Since(cn.lastBecameInterested)
221 func (cn *Peer) peerHasAllPieces() (all bool, known bool) {
222 if cn.peerSentHaveAll {
225 if !cn.t.haveInfo() {
228 return bitmap.Flip(cn._peerPieces, 0, bitmap.BitIndex(cn.t.numPieces())).IsEmpty(), true
231 func (cn *PeerConn) locker() *lockWithDeferreds {
232 return cn.t.cl.locker()
235 func (cn *Peer) supportsExtension(ext pp.ExtensionName) bool {
236 _, ok := cn.PeerExtensionIDs[ext]
240 // The best guess at number of pieces in the torrent for this peer.
241 func (cn *Peer) bestPeerNumPieces() pieceIndex {
243 return cn.t.numPieces()
245 return cn.peerMinPieces
248 func (cn *Peer) completedString() string {
249 have := pieceIndex(cn._peerPieces.Len())
250 if cn.peerSentHaveAll {
251 have = cn.bestPeerNumPieces()
253 return fmt.Sprintf("%d/%d", have, cn.bestPeerNumPieces())
256 func (cn *PeerConn) onGotInfo(info *metainfo.Info) {
257 cn.setNumPieces(info.NumPieces())
260 // Correct the PeerPieces slice length. Return false if the existing slice is invalid, such as by
261 // receiving badly sized BITFIELD, or invalid HAVE messages.
262 func (cn *PeerConn) setNumPieces(num pieceIndex) {
263 cn._peerPieces.RemoveRange(bitmap.BitIndex(num), bitmap.ToEnd)
264 cn.peerPiecesChanged()
267 func eventAgeString(t time.Time) string {
271 return fmt.Sprintf("%.2fs ago", time.Since(t).Seconds())
274 func (cn *PeerConn) connectionFlags() (ret string) {
276 ret += string([]byte{b})
278 if cn.cryptoMethod == mse.CryptoMethodRC4 {
280 } else if cn.headerEncrypted {
283 ret += string(cn.Discovery)
290 func (cn *PeerConn) utp() bool {
291 return parseNetworkString(cn.Network).Udp
294 // Inspired by https://github.com/transmission/transmission/wiki/Peer-Status-Text.
295 func (cn *Peer) statusFlags() (ret string) {
297 ret += string([]byte{b})
306 ret += cn.connectionFlags()
308 if cn.peerInterested {
317 func (cn *Peer) downloadRate() float64 {
318 num := cn._stats.BytesReadUsefulData.Int64()
322 return float64(num) / cn.totalExpectingTime().Seconds()
325 func (cn *Peer) numRequestsByPiece() (ret map[pieceIndex]int) {
326 ret = make(map[pieceIndex]int)
327 for r := range cn.requests {
328 ret[pieceIndex(r.Index)]++
333 func (cn *Peer) writeStatus(w io.Writer, t *Torrent) {
334 // \t isn't preserved in <pre> blocks?
335 if cn.closed.IsSet() {
336 fmt.Fprint(w, "CLOSED: ")
338 fmt.Fprintln(w, cn.connStatusString())
339 prio, err := cn.peerPriority()
340 prioStr := fmt.Sprintf("%08x", prio)
342 prioStr += ": " + err.Error()
344 fmt.Fprintf(w, " bep40-prio: %v\n", prioStr)
345 fmt.Fprintf(w, " last msg: %s, connected: %s, last helpful: %s, itime: %s, etime: %s\n",
346 eventAgeString(cn.lastMessageReceived),
347 eventAgeString(cn.completedHandshake),
348 eventAgeString(cn.lastHelpful()),
350 cn.totalExpectingTime(),
353 " %s completed, %d pieces touched, good chunks: %v/%v-%v reqq: %d/(%d/%d)-%d/%d, flags: %s, dr: %.1f KiB/s\n",
354 cn.completedString(),
355 len(cn.peerTouchedPieces),
356 &cn._stats.ChunksReadUseful,
357 &cn._stats.ChunksRead,
358 &cn._stats.ChunksWritten,
359 cn.numLocalRequests(),
360 cn.nominalMaxRequests(),
362 len(cn.peerRequests),
365 cn.downloadRate()/(1<<10),
367 fmt.Fprintf(w, " requested pieces:")
368 for piece, count := range cn.numRequestsByPiece() {
369 fmt.Fprintf(w, " %v (%v)", piece, count)
374 func (p *Peer) close() {
378 p.discardPieceInclination()
379 p._pieceRequestOrder.Clear()
381 p.t.decPeerPieceAvailability(p)
382 for _, f := range p.callbacks.PeerClosed {
387 func (cn *PeerConn) onClose() {
388 if cn.pex.IsEnabled() {
395 if cb := cn.callbacks.PeerConnClosed; cb != nil {
400 func (cn *Peer) peerHasPiece(piece pieceIndex) bool {
401 return cn.peerSentHaveAll || cn._peerPieces.Contains(bitmap.BitIndex(piece))
404 // 64KiB, but temporarily less to work around an issue with WebRTC. TODO: Update when
405 // https://github.com/pion/datachannel/issues/59 is fixed.
406 const writeBufferHighWaterLen = 1 << 15
408 // Writes a message into the write buffer. Returns whether it's okay to keep writing. Writing is
409 // done asynchronously, so it may be that we're not able to honour backpressure from this method.
410 func (cn *PeerConn) write(msg pp.Message) bool {
411 torrent.Add(fmt.Sprintf("messages written of type %s", msg.Type.String()), 1)
412 // We don't need to track bytes here because a connection.w Writer wrapper takes care of that
413 // (although there's some delay between us recording the message, and the connection writer
414 // flushing it out.).
415 cn.writeBuffer.Write(msg.MustMarshalBinary())
416 // Last I checked only Piece messages affect stats, and we don't write those.
419 return !cn.writeBufferFull()
422 func (cn *PeerConn) writeBufferFull() bool {
423 return cn.writeBuffer.Len() >= writeBufferHighWaterLen
426 func (cn *PeerConn) requestMetadataPiece(index int) {
427 eID := cn.PeerExtensionIDs[pp.ExtensionNameMetadata]
431 if index < len(cn.metadataRequests) && cn.metadataRequests[index] {
434 cn.logger.WithDefaultLevel(log.Debug).Printf("requesting metadata piece %d", index)
438 ExtendedPayload: func() []byte {
439 b, err := bencode.Marshal(map[string]int{
440 "msg_type": pp.RequestMetadataExtensionMsgType,
449 for index >= len(cn.metadataRequests) {
450 cn.metadataRequests = append(cn.metadataRequests, false)
452 cn.metadataRequests[index] = true
455 func (cn *PeerConn) requestedMetadataPiece(index int) bool {
456 return index < len(cn.metadataRequests) && cn.metadataRequests[index]
459 // The actual value to use as the maximum outbound requests.
460 func (cn *Peer) nominalMaxRequests() (ret int) {
461 return int(clamp(1, int64(cn.PeerMaxRequests), 64))
464 func (cn *Peer) totalExpectingTime() (ret time.Duration) {
465 ret = cn.cumulativeExpectedToReceiveChunks
466 if !cn.lastStartedExpectingToReceiveChunks.IsZero() {
467 ret += time.Since(cn.lastStartedExpectingToReceiveChunks)
473 func (cn *PeerConn) onPeerSentCancel(r Request) {
474 if _, ok := cn.peerRequests[r]; !ok {
475 torrent.Add("unexpected cancels received", 1)
478 if cn.fastEnabled() {
481 delete(cn.peerRequests, r)
485 func (cn *PeerConn) choke(msg messageWriter) (more bool) {
490 more = msg(pp.Message{
493 if cn.fastEnabled() {
494 for r := range cn.peerRequests {
495 // TODO: Don't reject pieces in allowed fast set.
499 cn.peerRequests = nil
504 func (cn *PeerConn) unchoke(msg func(pp.Message) bool) bool {
509 return msg(pp.Message{
514 func (cn *Peer) setInterested(interested bool) bool {
515 if cn.interested == interested {
518 cn.interested = interested
520 cn.lastBecameInterested = time.Now()
521 } else if !cn.lastBecameInterested.IsZero() {
522 cn.priorInterest += time.Since(cn.lastBecameInterested)
524 cn.updateExpectingChunks()
525 // log.Printf("%p: setting interest: %v", cn, interested)
526 return cn.writeInterested(interested)
529 func (pc *PeerConn) writeInterested(interested bool) bool {
530 return pc.write(pp.Message{
531 Type: func() pp.MessageType {
535 return pp.NotInterested
541 // The function takes a message to be sent, and returns true if more messages
543 type messageWriter func(pp.Message) bool
545 func (cn *Peer) request(r Request) error {
546 if _, ok := cn.requests[r]; ok {
549 if cn.numLocalRequests() >= cn.nominalMaxRequests() {
550 return errors.New("too many outstanding requests")
552 if !cn.peerHasPiece(pieceIndex(r.Index)) {
553 return errors.New("requesting piece peer doesn't have")
555 if !cn.t.peerIsActive(cn) {
556 panic("requesting but not in active conns")
558 if cn.closed.IsSet() {
559 panic("requesting when connection is closed")
561 if cn.t.hashingPiece(pieceIndex(r.Index)) {
562 panic("piece is being hashed")
564 if cn.t.pieceQueuedForHash(pieceIndex(r.Index)) {
565 panic("piece is queued for hash")
567 if !cn.setInterested(true) {
568 return errors.New("write buffer full after expressing interest")
571 if cn.peerAllowedFast.Get(int(r.Index)) {
572 torrent.Add("allowed fast requests sent", 1)
574 errors.New("peer choking and piece not in allowed fast set")
577 if cn.requests == nil {
578 cn.requests = make(map[Request]struct{})
580 cn.requests[r] = struct{}{}
581 if cn.validReceiveChunks == nil {
582 cn.validReceiveChunks = make(map[Request]int)
584 cn.validReceiveChunks[r]++
585 cn.t.pendingRequests[r]++
586 cn.updateExpectingChunks()
587 for _, f := range cn.callbacks.SentRequest {
588 f(PeerRequestEvent{cn, r})
590 cn.peerImpl._request(r)
594 func (me *PeerConn) _request(r Request) {
603 func (me *Peer) cancel(r Request) {
604 if me.deleteRequest(r) {
605 me.peerImpl._cancel(r)
609 func (me *PeerConn) _cancel(r Request) {
610 me.write(makeCancelMessage(r))
613 func (cn *PeerConn) fillWriteBuffer() {
614 if cn.pex.IsEnabled() {
615 if flow := cn.pex.Share(cn.write); !flow {
622 // Routine that writes to the peer. Some of what to write is buffered by
623 // activity elsewhere in the Client, and some is determined locally when the
624 // connection is writable.
625 func (cn *PeerConn) writer(keepAliveTimeout time.Duration) {
627 lastWrite time.Time = time.Now()
628 keepAliveTimer *time.Timer
630 keepAliveTimer = time.AfterFunc(keepAliveTimeout, func() {
632 defer cn.locker().Unlock()
633 if time.Since(lastWrite) >= keepAliveTimeout {
636 keepAliveTimer.Reset(keepAliveTimeout)
639 defer cn.locker().Unlock()
641 defer keepAliveTimer.Stop()
642 frontBuf := new(bytes.Buffer)
644 if cn.closed.IsSet() {
647 if cn.writeBuffer.Len() == 0 {
650 if cn.writeBuffer.Len() == 0 && time.Since(lastWrite) >= keepAliveTimeout && cn.useful() {
651 cn.writeBuffer.Write(pp.Message{Keepalive: true}.MustMarshalBinary())
652 torrent.Add("written keepalives", 1)
654 if cn.writeBuffer.Len() == 0 {
655 // TODO: Minimize wakeups....
660 frontBuf, cn.writeBuffer = cn.writeBuffer, frontBuf
662 n, err := cn.w.Write(frontBuf.Bytes())
665 lastWrite = time.Now()
666 keepAliveTimer.Reset(keepAliveTimeout)
669 cn.logger.WithDefaultLevel(log.Debug).Printf("error writing: %v", err)
672 if n != frontBuf.Len() {
679 func (cn *PeerConn) have(piece pieceIndex) {
680 if cn.sentHaves.Get(bitmap.BitIndex(piece)) {
685 Index: pp.Integer(piece),
687 cn.sentHaves.Add(bitmap.BitIndex(piece))
690 func (cn *PeerConn) postBitfield() {
691 if cn.sentHaves.Len() != 0 {
692 panic("bitfield must be first have-related message sent")
694 if !cn.t.haveAnyPieces() {
699 Bitfield: cn.t.bitfield(),
701 cn.sentHaves = cn.t._completedPieces.Copy()
704 func (cn *PeerConn) updateRequests() {
705 // log.Print("update requests")
709 // Emits the indices in the Bitmaps bms in order, never repeating any index.
710 // skip is mutated during execution, and its initial values will never be
712 func iterBitmapsDistinct(skip *bitmap.Bitmap, bms ...bitmap.Bitmap) iter.Func {
713 return func(cb iter.Callback) {
714 for _, bm := range bms {
716 func(_i interface{}) bool {
718 if skip.Contains(i) {
732 // check callers updaterequests
733 func (cn *Peer) stopRequestingPiece(piece pieceIndex) bool {
734 return cn._pieceRequestOrder.Remove(bitmap.BitIndex(piece))
737 // This is distinct from Torrent piece priority, which is the user's
738 // preference. Connection piece priority is specific to a connection and is
739 // used to pseudorandomly avoid connections always requesting the same pieces
740 // and thus wasting effort.
741 func (cn *Peer) updatePiecePriority(piece pieceIndex) bool {
742 tpp := cn.t.piecePriority(piece)
743 if !cn.peerHasPiece(piece) {
744 tpp = PiecePriorityNone
746 if tpp == PiecePriorityNone {
747 return cn.stopRequestingPiece(piece)
749 prio := cn.getPieceInclination()[piece]
750 return cn._pieceRequestOrder.Set(bitmap.BitIndex(piece), prio)
753 func (cn *Peer) getPieceInclination() []int {
754 if cn.pieceInclination == nil {
755 cn.pieceInclination = cn.t.getConnPieceInclination()
757 return cn.pieceInclination
760 func (cn *Peer) discardPieceInclination() {
761 if cn.pieceInclination == nil {
764 cn.t.putPieceInclination(cn.pieceInclination)
765 cn.pieceInclination = nil
768 func (cn *Peer) peerPiecesChanged() {
770 prioritiesChanged := false
771 for i := pieceIndex(0); i < cn.t.numPieces(); i++ {
772 if cn.updatePiecePriority(i) {
773 prioritiesChanged = true
776 if prioritiesChanged {
780 cn.t.maybeDropMutuallyCompletePeer(cn)
783 func (cn *PeerConn) raisePeerMinPieces(newMin pieceIndex) {
784 if newMin > cn.peerMinPieces {
785 cn.peerMinPieces = newMin
789 func (cn *PeerConn) peerSentHave(piece pieceIndex) error {
790 if cn.t.haveInfo() && piece >= cn.t.numPieces() || piece < 0 {
791 return errors.New("invalid piece")
793 if cn.peerHasPiece(piece) {
796 cn.raisePeerMinPieces(piece + 1)
797 if !cn.peerHasPiece(piece) {
798 cn.t.incPieceAvailability(piece)
800 cn._peerPieces.Set(bitmap.BitIndex(piece), true)
801 cn.t.maybeDropMutuallyCompletePeer(&cn.Peer)
802 if cn.updatePiecePriority(piece) {
808 func (cn *PeerConn) peerSentBitfield(bf []bool) error {
810 panic("expected bitfield length divisible by 8")
812 // We know that the last byte means that at most the last 7 bits are wasted.
813 cn.raisePeerMinPieces(pieceIndex(len(bf) - 7))
814 if cn.t.haveInfo() && len(bf) > int(cn.t.numPieces()) {
815 // Ignore known excess pieces.
816 bf = bf[:cn.t.numPieces()]
818 pp := cn.newPeerPieces()
819 cn.peerSentHaveAll = false
820 for i, have := range bf {
822 cn.raisePeerMinPieces(pieceIndex(i) + 1)
824 cn.t.incPieceAvailability(i)
828 cn.t.decPieceAvailability(i)
831 cn._peerPieces.Set(i, have)
833 cn.peerPiecesChanged()
837 func (cn *Peer) onPeerHasAllPieces() {
840 pp := cn.newPeerPieces()
841 for i := range iter.N(t.numPieces()) {
843 t.incPieceAvailability(i)
847 cn.peerSentHaveAll = true
848 cn._peerPieces.Clear()
849 cn.peerPiecesChanged()
852 func (cn *PeerConn) onPeerSentHaveAll() error {
853 cn.onPeerHasAllPieces()
857 func (cn *PeerConn) peerSentHaveNone() error {
858 cn.t.decPeerPieceAvailability(&cn.Peer)
859 cn._peerPieces.Clear()
860 cn.peerSentHaveAll = false
861 cn.peerPiecesChanged()
865 func (c *PeerConn) requestPendingMetadata() {
869 if c.PeerExtensionIDs[pp.ExtensionNameMetadata] == 0 {
870 // Peer doesn't support this.
873 // Request metadata pieces that we don't have in a random order.
875 for index := 0; index < c.t.metadataPieceCount(); index++ {
876 if !c.t.haveMetadataPiece(index) && !c.requestedMetadataPiece(index) {
877 pending = append(pending, index)
880 rand.Shuffle(len(pending), func(i, j int) { pending[i], pending[j] = pending[j], pending[i] })
881 for _, i := range pending {
882 c.requestMetadataPiece(i)
886 func (cn *PeerConn) wroteMsg(msg *pp.Message) {
887 torrent.Add(fmt.Sprintf("messages written of type %s", msg.Type.String()), 1)
888 if msg.Type == pp.Extended {
889 for name, id := range cn.PeerExtensionIDs {
890 if id != msg.ExtendedID {
893 torrent.Add(fmt.Sprintf("Extended messages written for protocol %q", name), 1)
896 cn.allStats(func(cs *ConnStats) { cs.wroteMsg(msg) })
899 func (cn *PeerConn) readMsg(msg *pp.Message) {
900 cn.allStats(func(cs *ConnStats) { cs.readMsg(msg) })
903 // After handshake, we know what Torrent and Client stats to include for a
905 func (cn *Peer) postHandshakeStats(f func(*ConnStats)) {
911 // All ConnStats that include this connection. Some objects are not known
912 // until the handshake is complete, after which it's expected to reconcile the
914 func (cn *Peer) allStats(f func(*ConnStats)) {
916 if cn.reconciledHandshakeStats {
917 cn.postHandshakeStats(f)
921 func (cn *PeerConn) wroteBytes(n int64) {
922 cn.allStats(add(n, func(cs *ConnStats) *Count { return &cs.BytesWritten }))
925 func (cn *PeerConn) readBytes(n int64) {
926 cn.allStats(add(n, func(cs *ConnStats) *Count { return &cs.BytesRead }))
929 // Returns whether the connection could be useful to us. We're seeding and
930 // they want data, we don't have metainfo and they can provide it, etc.
931 func (c *Peer) useful() bool {
933 if c.closed.IsSet() {
937 return c.supportsExtension("ut_metadata")
939 if t.seeding() && c.peerInterested {
942 if c.peerHasWantedPieces() {
948 func (c *Peer) lastHelpful() (ret time.Time) {
949 ret = c.lastUsefulChunkReceived
950 if c.t.seeding() && c.lastChunkSent.After(ret) {
951 ret = c.lastChunkSent
956 func (c *PeerConn) fastEnabled() bool {
957 return c.PeerExtensionBytes.SupportsFast() && c.t.cl.config.Extensions.SupportsFast()
960 func (c *PeerConn) reject(r Request) {
961 if !c.fastEnabled() {
962 panic("fast not enabled")
964 c.write(r.ToMsg(pp.Reject))
965 delete(c.peerRequests, r)
968 func (c *PeerConn) onReadRequest(r Request) error {
969 requestedChunkLengths.Add(strconv.FormatUint(r.Length.Uint64(), 10), 1)
970 if _, ok := c.peerRequests[r]; ok {
971 torrent.Add("duplicate requests received", 1)
975 torrent.Add("requests received while choking", 1)
977 torrent.Add("requests rejected while choking", 1)
982 if len(c.peerRequests) >= maxRequests {
983 torrent.Add("requests received while queue full", 1)
987 // BEP 6 says we may close here if we choose.
990 if !c.t.havePiece(pieceIndex(r.Index)) {
991 // This isn't necessarily them screwing up. We can drop pieces
992 // from our storage, and can't communicate this to peers
993 // except by reconnecting.
994 requestsReceivedForMissingPieces.Add(1)
995 return fmt.Errorf("peer requested piece we don't have: %v", r.Index.Int())
997 // Check this after we know we have the piece, so that the piece length will be known.
998 if r.Begin+r.Length > c.t.pieceLength(pieceIndex(r.Index)) {
999 torrent.Add("bad requests received", 1)
1000 return errors.New("bad Request")
1002 if c.peerRequests == nil {
1003 c.peerRequests = make(map[Request]*peerRequestState, maxRequests)
1005 value := &peerRequestState{}
1006 c.peerRequests[r] = value
1007 go c.peerRequestDataReader(r, value)
1012 func (c *PeerConn) peerRequestDataReader(r Request, prs *peerRequestState) {
1013 b, err := readPeerRequestData(r, c)
1015 defer c.locker().Unlock()
1017 c.peerRequestDataReadFailed(err, r)
1020 panic("data must be non-nil to trigger send")
1027 // If this is maintained correctly, we might be able to support optional synchronous reading for
1028 // chunk sending, the way it used to work.
1029 func (c *PeerConn) peerRequestDataReadFailed(err error, r Request) {
1030 c.logger.WithDefaultLevel(log.Warning).Printf("error reading chunk for peer Request %v: %v", r, err)
1031 i := pieceIndex(r.Index)
1032 if c.t.pieceComplete(i) {
1033 // There used to be more code here that just duplicated the following break. Piece
1034 // completions are currently cached, so I'm not sure how helpful this update is, except to
1035 // pull any completion changes pushed to the storage backend in failed reads that got us
1037 c.t.updatePieceCompletion(i)
1039 // If we failed to send a chunk, choke the peer to ensure they flush all their requests. We've
1040 // probably dropped a piece from storage, but there's no way to communicate this to the peer. If
1041 // they ask for it again, we'll kick them to allow us to send them an updated bitfield on the
1042 // next connect. TODO: Support rejecting here too.
1044 c.logger.WithDefaultLevel(log.Warning).Printf("already choking peer, requests might not be rejected correctly")
1049 func readPeerRequestData(r Request, c *PeerConn) ([]byte, error) {
1050 b := make([]byte, r.Length)
1051 p := c.t.info.Piece(int(r.Index))
1052 n, err := c.t.readAt(b, p.Offset()+int64(r.Begin))
1059 panic("expected error")
1065 func runSafeExtraneous(f func()) {
1073 // Processes incoming BitTorrent wire-protocol messages. The client lock is held upon entry and
1074 // exit. Returning will end the connection.
1075 func (c *PeerConn) mainReadLoop() (err error) {
1078 torrent.Add("connection.mainReadLoop returned with error", 1)
1080 torrent.Add("connection.mainReadLoop returned with no error", 1)
1086 decoder := pp.Decoder{
1087 R: bufio.NewReaderSize(c.r, 1<<17),
1088 MaxLength: 256 * 1024,
1096 err = decoder.Decode(&msg)
1098 if cb := c.callbacks.ReadMessage; cb != nil && err == nil {
1101 if t.closed.IsSet() || c.closed.IsSet() {
1108 c.lastMessageReceived = time.Now()
1110 receivedKeepalives.Add(1)
1113 messageTypesReceived.Add(msg.Type.String(), 1)
1114 if msg.Type.FastExtension() && !c.fastEnabled() {
1115 runSafeExtraneous(func() { torrent.Add("fast messages received when extension is disabled", 1) })
1116 return fmt.Errorf("received fast extension message (type=%v) but extension is disabled", msg.Type)
1120 c.peerChoking = true
1121 if !c.fastEnabled() {
1122 c.deleteAllRequests()
1124 // We can then reset our interest.
1126 c.updateExpectingChunks()
1128 c.peerChoking = false
1130 c.updateExpectingChunks()
1132 c.peerInterested = true
1134 case pp.NotInterested:
1135 c.peerInterested = false
1136 // We don't clear their requests since it isn't clear in the spec.
1137 // We'll probably choke them for this, which will clear them if
1138 // appropriate, and is clearly specified.
1140 err = c.peerSentHave(pieceIndex(msg.Index))
1142 err = c.peerSentBitfield(msg.Bitfield)
1144 r := newRequestFromMessage(&msg)
1145 err = c.onReadRequest(r)
1147 err = c.receiveChunk(&msg)
1148 if len(msg.Piece) == int(t.chunkSize) {
1149 t.chunkPool.Put(&msg.Piece)
1152 err = fmt.Errorf("receiving chunk: %s", err)
1155 req := newRequestFromMessage(&msg)
1156 c.onPeerSentCancel(req)
1158 ipa, ok := tryIpPortFromNetAddr(c.RemoteAddr)
1162 pingAddr := net.UDPAddr{
1167 pingAddr.Port = int(msg.Port)
1169 cl.eachDhtServer(func(s DhtServer) {
1170 go s.Ping(&pingAddr)
1173 torrent.Add("suggests received", 1)
1174 log.Fmsg("peer suggested piece %d", msg.Index).AddValues(c, msg.Index).SetLevel(log.Debug).Log(c.t.logger)
1177 err = c.onPeerSentHaveAll()
1179 err = c.peerSentHaveNone()
1181 c.remoteRejectedRequest(newRequestFromMessage(&msg))
1182 case pp.AllowedFast:
1183 torrent.Add("allowed fasts received", 1)
1184 log.Fmsg("peer allowed fast: %d", msg.Index).AddValues(c).SetLevel(log.Debug).Log(c.t.logger)
1185 c.peerAllowedFast.Add(int(msg.Index))
1188 err = c.onReadExtendedMsg(msg.ExtendedID, msg.ExtendedPayload)
1190 err = fmt.Errorf("received unknown message type: %#v", msg.Type)
1198 func (c *Peer) remoteRejectedRequest(r Request) {
1199 if c.deleteRequest(r) {
1200 c.decExpectedChunkReceive(r)
1204 func (c *Peer) decExpectedChunkReceive(r Request) {
1205 count := c.validReceiveChunks[r]
1207 delete(c.validReceiveChunks, r)
1208 } else if count > 1 {
1209 c.validReceiveChunks[r] = count - 1
1215 func (c *PeerConn) onReadExtendedMsg(id pp.ExtensionNumber, payload []byte) (err error) {
1217 // TODO: Should we still do this?
1219 // These clients use their own extension IDs for outgoing message
1220 // types, which is incorrect.
1221 if bytes.HasPrefix(c.PeerID[:], []byte("-SD0100-")) || strings.HasPrefix(string(c.PeerID[:]), "-XL0012-") {
1229 case pp.HandshakeExtendedID:
1230 var d pp.ExtendedHandshakeMessage
1231 if err := bencode.Unmarshal(payload, &d); err != nil {
1232 c.logger.Printf("error parsing extended handshake message %q: %s", payload, err)
1233 return fmt.Errorf("unmarshalling extended handshake payload: %w", err)
1235 if cb := c.callbacks.ReadExtendedHandshake; cb != nil {
1238 //c.logger.WithDefaultLevel(log.Debug).Printf("received extended handshake message:\n%s", spew.Sdump(d))
1240 c.PeerMaxRequests = d.Reqq
1242 c.PeerClientName = d.V
1243 if c.PeerExtensionIDs == nil {
1244 c.PeerExtensionIDs = make(map[pp.ExtensionName]pp.ExtensionNumber, len(d.M))
1246 c.PeerListenPort = d.Port
1247 c.PeerPrefersEncryption = d.Encryption
1248 for name, id := range d.M {
1249 if _, ok := c.PeerExtensionIDs[name]; !ok {
1250 peersSupportingExtension.Add(string(name), 1)
1252 c.PeerExtensionIDs[name] = id
1254 if d.MetadataSize != 0 {
1255 if err = t.setMetadataSize(d.MetadataSize); err != nil {
1256 return fmt.Errorf("setting metadata size to %d: %w", d.MetadataSize, err)
1259 c.requestPendingMetadata()
1260 if !t.cl.config.DisablePEX {
1261 t.pex.Add(c) // we learnt enough now
1265 case metadataExtendedId:
1266 err := cl.gotMetadataExtensionMsg(payload, t, c)
1268 return fmt.Errorf("handling metadata extension message: %w", err)
1272 if !c.pex.IsEnabled() {
1273 return nil // or hang-up maybe?
1275 return c.pex.Recv(payload)
1277 return fmt.Errorf("unexpected extended message ID: %v", id)
1281 // Set both the Reader and Writer for the connection from a single ReadWriter.
1282 func (cn *PeerConn) setRW(rw io.ReadWriter) {
1287 // Returns the Reader and Writer as a combined ReadWriter.
1288 func (cn *PeerConn) rw() io.ReadWriter {
1295 // Handle a received chunk from a peer.
1296 func (c *Peer) receiveChunk(msg *pp.Message) error {
1299 chunksReceived.Add("total", 1)
1301 req := newRequestFromMessage(msg)
1304 chunksReceived.Add("while choked", 1)
1307 if c.validReceiveChunks[req] <= 0 {
1308 chunksReceived.Add("unexpected", 1)
1309 return errors.New("received unexpected chunk")
1311 c.decExpectedChunkReceive(req)
1313 if c.peerChoking && c.peerAllowedFast.Get(int(req.Index)) {
1314 chunksReceived.Add("due to allowed fast", 1)
1317 // The request needs to be deleted immediately to prevent cancels occurring asynchronously when
1318 // have actually already received the piece, while we have the Client unlocked to write the data
1320 deletedRequest := false
1322 if _, ok := c.requests[req]; ok {
1323 for _, f := range c.callbacks.ReceivedRequested {
1324 f(PeerMessageEvent{c, msg})
1327 // Request has been satisfied.
1328 if c.deleteRequest(req) {
1329 deletedRequest = true
1331 c._chunksReceivedWhileExpecting++
1334 chunksReceived.Add("unwanted", 1)
1338 // Do we actually want this chunk?
1339 if t.haveChunk(req) {
1340 chunksReceived.Add("wasted", 1)
1341 c.allStats(add(1, func(cs *ConnStats) *Count { return &cs.ChunksReadWasted }))
1345 piece := &t.pieces[req.Index]
1347 c.allStats(add(1, func(cs *ConnStats) *Count { return &cs.ChunksReadUseful }))
1348 c.allStats(add(int64(len(msg.Piece)), func(cs *ConnStats) *Count { return &cs.BytesReadUsefulData }))
1350 c.allStats(add(int64(len(msg.Piece)), func(cs *ConnStats) *Count { return &cs.BytesReadUsefulIntendedData }))
1352 for _, f := range c.t.cl.config.Callbacks.ReceivedUsefulData {
1353 f(ReceivedUsefulDataEvent{c, msg})
1355 c.lastUsefulChunkReceived = time.Now()
1357 // Need to record that it hasn't been written yet, before we attempt to do
1358 // anything with it.
1359 piece.incrementPendingWrites()
1360 // Record that we have the chunk, so we aren't trying to download it while
1361 // waiting for it to be written to storage.
1362 piece.unpendChunkIndex(chunkIndex(req.ChunkSpec, t.chunkSize))
1364 // Cancel pending requests for this chunk from *other* peers.
1365 t.iterPeers(func(p *Peer) {
1372 err := func() error {
1375 concurrentChunkWrites.Add(1)
1376 defer concurrentChunkWrites.Add(-1)
1377 // Write the chunk out. Note that the upper bound on chunk writing concurrency will be the
1378 // number of connections. We write inline with receiving the chunk (with this lock dance),
1379 // because we want to handle errors synchronously and I haven't thought of a nice way to
1380 // defer any concurrency to the storage and have that notify the client of errors. TODO: Do
1382 return t.writeChunk(int(msg.Index), int64(msg.Begin), msg.Piece)
1385 piece.decrementPendingWrites()
1388 c.logger.WithDefaultLevel(log.Error).Printf("writing received chunk %v: %v", req, err)
1390 //t.updatePieceCompletion(pieceIndex(msg.Index))
1391 t.onWriteChunkErr(err)
1395 c.onDirtiedPiece(pieceIndex(req.Index))
1397 // We need to ensure the piece is only queued once, so only the last chunk writer gets this job.
1398 if t.pieceAllDirty(pieceIndex(req.Index)) && piece.pendingWrites == 0 {
1399 t.queuePieceCheck(pieceIndex(req.Index))
1400 // We don't pend all chunks here anymore because we don't want code dependent on the dirty
1401 // chunk status (such as the haveChunk call above) to have to check all the various other
1402 // piece states like queued for hash, hashing etc. This does mean that we need to be sure
1403 // that chunk pieces are pended at an appropriate time later however.
1406 cl.event.Broadcast()
1407 // We do this because we've written a chunk, and may change PieceState.Partial.
1408 t.publishPieceChange(pieceIndex(req.Index))
1413 func (c *Peer) onDirtiedPiece(piece pieceIndex) {
1414 if c.peerTouchedPieces == nil {
1415 c.peerTouchedPieces = make(map[pieceIndex]struct{})
1417 c.peerTouchedPieces[piece] = struct{}{}
1418 ds := &c.t.pieces[piece].dirtiers
1420 *ds = make(map[*Peer]struct{})
1422 (*ds)[c] = struct{}{}
1425 func (c *PeerConn) uploadAllowed() bool {
1426 if c.t.cl.config.NoUpload {
1429 if c.t.dataUploadDisallowed {
1435 if !c.peerHasWantedPieces() {
1438 // Don't upload more than 100 KiB more than we download.
1439 if c._stats.BytesWrittenData.Int64() >= c._stats.BytesReadData.Int64()+100<<10 {
1445 func (c *PeerConn) setRetryUploadTimer(delay time.Duration) {
1446 if c.uploadTimer == nil {
1447 c.uploadTimer = time.AfterFunc(delay, c.writerCond.Broadcast)
1449 c.uploadTimer.Reset(delay)
1453 // Also handles choking and unchoking of the remote peer.
1454 func (c *PeerConn) upload(msg func(pp.Message) bool) bool {
1455 // Breaking or completing this loop means we don't want to upload to the
1456 // peer anymore, and we choke them.
1458 for c.uploadAllowed() {
1459 // We want to upload to the peer.
1460 if !c.unchoke(msg) {
1463 for r, state := range c.peerRequests {
1464 if state.data == nil {
1467 res := c.t.cl.config.UploadRateLimiter.ReserveN(time.Now(), int(r.Length))
1469 panic(fmt.Sprintf("upload rate limiter burst size < %d", r.Length))
1471 delay := res.Delay()
1474 c.setRetryUploadTimer(delay)
1475 // Hard to say what to return here.
1478 more := c.sendChunk(r, msg, state)
1479 delete(c.peerRequests, r)
1490 func (cn *PeerConn) drop() {
1491 cn.t.dropConnection(cn)
1494 func (cn *Peer) netGoodPiecesDirtied() int64 {
1495 return cn._stats.PiecesDirtiedGood.Int64() - cn._stats.PiecesDirtiedBad.Int64()
1498 func (c *Peer) peerHasWantedPieces() bool {
1499 return !c._pieceRequestOrder.IsEmpty()
1502 func (c *Peer) numLocalRequests() int {
1503 return len(c.requests)
1506 func (c *Peer) deleteRequest(r Request) bool {
1507 if _, ok := c.requests[r]; !ok {
1510 delete(c.requests, r)
1511 for _, f := range c.callbacks.DeletedRequest {
1512 f(PeerRequestEvent{c, r})
1514 c.updateExpectingChunks()
1515 pr := c.t.pendingRequests
1527 func (c *Peer) deleteAllRequests() {
1528 for r := range c.requests {
1531 if len(c.requests) != 0 {
1532 panic(len(c.requests))
1534 // for c := range c.t.conns {
1539 // This is called when something has changed that should wake the writer, such as putting stuff into
1540 // the writeBuffer, or changing some state that the writer can act on.
1541 func (c *PeerConn) tickleWriter() {
1542 c.writerCond.Broadcast()
1545 func (c *PeerConn) sendChunk(r Request, msg func(pp.Message) bool, state *peerRequestState) (more bool) {
1546 c.lastChunkSent = time.Now()
1547 return msg(pp.Message{
1555 func (c *PeerConn) setTorrent(t *Torrent) {
1557 panic("connection already associated with a torrent")
1560 c.logger.WithDefaultLevel(log.Debug).Printf("set torrent=%v", t)
1561 t.reconcileHandshakeStats(c)
1564 func (c *Peer) peerPriority() (peerPriority, error) {
1565 return bep40Priority(c.remoteIpPort(), c.t.cl.publicAddr(c.remoteIp()))
1568 func (c *Peer) remoteIp() net.IP {
1569 host, _, _ := net.SplitHostPort(c.RemoteAddr.String())
1570 return net.ParseIP(host)
1573 func (c *Peer) remoteIpPort() IpPort {
1574 ipa, _ := tryIpPortFromNetAddr(c.RemoteAddr)
1575 return IpPort{ipa.IP, uint16(ipa.Port)}
1578 func (c *PeerConn) pexPeerFlags() pp.PexPeerFlags {
1579 f := pp.PexPeerFlags(0)
1580 if c.PeerPrefersEncryption {
1581 f |= pp.PexPrefersEncryption
1584 f |= pp.PexOutgoingConn
1587 f |= pp.PexSupportsUtp
1592 // This returns the address to use if we want to dial the peer again. It incorporates the peer's
1593 // advertised listen port.
1594 func (c *PeerConn) dialAddr() PeerRemoteAddr {
1595 if !c.outgoing && c.PeerListenPort != 0 {
1596 switch addr := c.RemoteAddr.(type) {
1599 dialAddr.Port = c.PeerListenPort
1603 dialAddr.Port = c.PeerListenPort
1610 func (c *PeerConn) pexEvent(t pexEventType) pexEvent {
1611 f := c.pexPeerFlags()
1612 addr := c.dialAddr()
1613 return pexEvent{t, addr, f}
1616 func (c *PeerConn) String() string {
1617 return fmt.Sprintf("connection %p", c)
1620 func (c *Peer) trust() connectionTrust {
1621 return connectionTrust{c.trusted, c.netGoodPiecesDirtied()}
1624 type connectionTrust struct {
1626 NetGoodPiecesDirted int64
1629 func (l connectionTrust) Less(r connectionTrust) bool {
1630 return multiless.New().Bool(l.Implicit, r.Implicit).Int64(l.NetGoodPiecesDirted, r.NetGoodPiecesDirted).Less()
1633 func (cn *Peer) peerMaxRequests() int {
1634 return cn.PeerMaxRequests
1637 // Returns the pieces the peer has claimed to have.
1638 func (cn *PeerConn) PeerPieces() bitmap.Bitmap {
1640 defer cn.locker().RUnlock()
1641 return cn.newPeerPieces()
1644 // Returns a new Bitmap that includes bits for all pieces we have.
1645 func (cn *Peer) newPeerPieces() bitmap.Bitmap {
1646 ret := cn._peerPieces.Copy()
1647 if cn.peerSentHaveAll {
1648 ret.AddRange(0, cn.t.numPieces())
1653 func (cn *Peer) pieceRequestOrder() *prioritybitmap.PriorityBitmap {
1654 return &cn._pieceRequestOrder
1657 func (cn *Peer) stats() *ConnStats {
1661 func (p *Peer) TryAsPeerConn() (*PeerConn, bool) {
1662 pc, ok := p.peerImpl.(*PeerConn)